Apple has stricter requirements for submitting Apps posted, As of April 2020, applications for iOS must be developed with the iOS 13 SDK or later. Interestingly enough, this is true not only for new products but also app updates. Apple emphasizes especially the new displays.
It is explicitly mentioned that the display of the iPhone Xs Max and the iPad Pro 12.9 (third generation) must be supported by the apps in the sense of an all-screen design. So Apple says a reasonable adjustment to the round corners of the devices as well as the Notch on the iPhone.
There is a limited requirement for Dark Mode. The developers are supposed to adapt their apps to the new color mode. Apple provides exceptions here. If the developer needs more time, he can decide by opt-out against the dark mode. In cases where the app is not intended for dark fashion, a permanent opt-out is provided. As part of this, Apple is currently warning of a problem in Xcode if explicitly named colors are used. Version 11 of iOS is causing problems here. Apple recommends that you either wait for the next XCode update or, for customers, set the minimum requirement for the app to iOS 12.
Apple's iOS 13 is currently distributed as a Goldmaster for developers. The release of the new operating system is expected shortly in parallel with the launch of Apple Arcade. The operating system is part of the launch of the new iPhone 11 Pro, but will also support older smartphones.